After fueling motorists for over a century, the internal combustion engine's days just might be numbered.

Signs of such an apocalypse may have been uncovered at last week's SAE World Congress auto tech show held in Detroit, where engineering firm Protean Electric showcased a Ford F-150 that's powered by a compact in-wheel electric motor. The technology, designed to replace entire intricate engine systems, is similar to the one found in SIM-Drive Corporation's LEI electric car, which boasts a 207-mile driving range and the ability to go from 0 to 60 in 4.8 seconds.

The recent exhibition is part of a growing trend in which researchers and major automotive companies have begun exploring experimental designs that make for more fuel efficient and lower emission cars.

Last month, I reported on a unique engine prototype that does away with vital components like transmissions, valves and crankshafts and instead relies on a sophisticated form of shockwave technology to achieve a fuel conversion rate of 60 percent, a marked improvement over the internal combustion engine's 15 percent conversion rate.

Not long after that, the Chrysler Group announced that they've partnered with the Environmental Protection Agency to produce a hybrid engine based on fuel efficient hydraulic hybrid systems used by larger vehicles like garbage and delivery trucks.

Although a vehicle that uses any of these alternative systems has yet to be mass produced (and who knows if it will ever happen), Protean's in-wheel propulsion system, known as "Protean Drive," can also be installed in most traditional cars. This form of conversion would give drivers the option of operating the car as an engine-only, electric-only or hybrid vehicle.

Besides improving fuel efficiency and reducing emissions, owners will also experience a very noticeable performance boost.

The F-150, one of Protean's U.S. show cars, uses four in-wheel motors. It can go 100-plus miles an hour and has a 100-mile range. But, Vallance pointed out, if you drop this powertrain into a smaller vehicle, you can go 0-60 in under five seconds and top out at 130+ mph. That's what the 2007 demonstrator, the Volvo ReCharge, could do. It also used Protean in-wheel motors.

Protean currently offers one in-wheel motor model, which is designed to fit inside a typical 18-inch road wheel. The plan is to get this motor certified, and then be able to get it ready for mass production in about 18 months. Once that happens, it could be scaled it up or down if future partners ask for it. Protean doesn't want to be in the business of converting cars, it just wants to perfect these motors and work with OEMs to get them into lots and lots of vehicles. You can get more information at the Protean website, including this spec-sheet PDF, and you can see pictures of the motors in our gallery below.